Hydrogenation of unsaturated fatty oils



Nov. 22, 1955 R. P. DUNMIRE 2,724,689

HYDROGENATION OF UNSATURATED FATTY OILS Filed Dec. 2, 1949 2Sheets-Sheet. l

INVENTOR Russell E Dunmire ATTORNEY &

2 Sheets-Sheet 2 INVENTOR Russell Dunmz're R. P. DUNMIRE I/l/l/ Nov. 22,1955 Filed Dec. 2, 1949 M ATTO NEY United States Patent Ofiice 2,724,689Patented Nov. 22, 1955 HYDRUGENATION F UNSATURA'IED FATTY OILS Thisinvention relates to improved methods and apparatus for carrying outcatalytic reactions and more particularly to the hydrogenation ofunsaturated fatty oils. This application is intended as acontinuation-in-part of my prior application, Ser. No. 519,572, filedJanuary 24, 1944, now abandoned, for Process of and Apparatus forCarrying Out Chemical Reactions.

In general, the hydrogenation of unsaturated fatty oils has beeneffected in the past by passing hydrogen gas through an oil While theoil is held in a suitable container in contact with a hydrogenationcatalyst and while maintaining the oil and the catalyst at an elevatedtemperature. The temperature may range from as low as about 120 F. toabove 400 F., depending upon the character of the oil being treated, thepressure employed, the rate and completeness of reaction desired, andother considerations which affect the character of the product.

Hydrogenation processes have been performed commercially both on a batchbasis and on a semi-continuous basis, and contact with the catalysthasbeen achieved either by suspending a powdered catalyst in the oil andsubsequently removing it by filtration or by employing a stationarycarrier having a large surface area coated with the catalyst material.These processes have involved supplying sensible heat to the oil andthence to the surfaces of the catalyst while the oil is maintained in ahydrogen atmosphere under an appreciable superatmospheric pressure.

The degree of hydrogenation and the progress of side reactions thatmodify the oils in other respects, depend, to a considerable extent,upon the operating conditions such as the temperature and pressureemployed, the rate of heat transfer, the rate of molecular contact ofreactants and catalyst, the presence of impurities in the oil" itself,in the hydrogen gas, or in the hydrogenation reactor, and the time towhich the oil is subjected to these variable conditions. The value ofthehydrogenated oil for various industrial purposes, therefore, isdependent to a considerable degree, upon the process employed and theprecise conditions of operation.

It is a generally accepted fact that the hydrogen must be dissolved inthe oil in order for hydrogenation to occur and that the hydrogenationreaction takes place at the interface between the hydrogen-laden oil andthe catalyst.

' sible heat supplied to the oil in the course of the process,.

Since the solubility of hydrogen in oil increases both with temperatureand pressure, it has been considered more or less essential for the oilitself to be maintained at a relatively high temperature to effect anysubstantial degree of hydrogenation within a reasonable time. However,high temperature tends to promote undesired chemical alteration ofunsaturated oils, as by polymerization, interesterification, anddecomposition, for example;

and the rate of hydrogenation may actually be reduced by the use oftemperatures above about 425 F. Thus, there has been a practical limitto the temperature that may be employed, particularly if the oil .is tobe held at the elevated temperature for a prolonged period of time.

This is especially true with respect to edible oils containing vitamins,amino acids, and hormones.

. In a batch operation, intimate mixing of the hydrogen with the oil isgenerally performed while the oil is held at the desired hydrogenationtemperature and in the presence of the catalyst. In continuousprocesses, the oil is first heated and charged with hydrogen to thelimit of its solubility at the temperature and pressure employed, andthe saturated oil, together with an excess of hydrogen, is run into areactor and over a stationary catalyst bed. This may be donecontinuously either by dripping or spraying the oil on the catalyst orby flooding the reactor with oil. Continuously withdrawn oil may be sentto storage, or recirculated for more complete hydrogenation. In anyevent, the oil is kept at the elevated temperature for a prolongedperiod of time in order to carry the process to completion.

Insofar as I am aware, the commercial processes for the hydrogenation ofunsaturated fatty oils have involved the use of some form of externallygenerated heat to raise the temperature of the entire oil mass to theselected reaction temperature range and to hold it in that range untilhydrogenation is complete.

A primary object of the invention is to provide a process and appaartusfor hydrogenating fatty oils without heating the oils prior to theactual hydrogenation step and while maintaining the mean oil temperatureat a minimum.

A further object of the invention is to provide a process and apparatusfor hydrogenating fatty oils at a more rapid rate than has heretoforebeen possible without employing objectionably high temperatures.

A further object of the invention is to provide a process and apparatusfor hydrogenating fatty oils with closer control of the degree ofhydrogenation and of the occurrence and progress of side reactionstending to modify the oils in other respects.

Still another object of the invention is to improve the thermalefliciency of processes for hydrogenation of fatty oils by keeping to aminimum the amount of senthus reducing heat losses as well as the hightemperatures inherent in present commercial practices.

A characteristic feature of the invention involves elimination of thenecessity for heating the oil for dissolving hydrogen therein. Anotherfeature of the invention is that the energy required to eifect theendothermic hydrogenation reaction is supplied directly to the catalyst,

rather than directly to the oil. Other objects and advantages of theinvention will become apparent from the following detailed descriptionof various embodiments thereof and of examples of the application of theinvention to the hydrogenation of specific oils.

The invention will first be described with reference to the accompanyingdrawings in which:

Figure 1 is an elevational view of one form of apparatus for carryingout the invention on a batch basis, some of the details of the apparatusbeing shown somewhat schematically;

Fig. 2 is an elevational view similar to Fig. 1, showing a modified formof a portion of the apparatus for carrying out the invention on acontinuous or semi-continuous basis;

Fig. 3 is a top view of one of the reactors shown in Fig. l; the reactorbeing shown partly in section as indicated by the line 33 in Fig. 4;

Fig. 4 is a vertical sectional view of the reactor of Fig. 3, the planeof the section being indicated by the line 4-4 in Fig. 3; and

Fig. 5 is a vertical sectional view similar to Fig. 4 but showing amodified form of reactor.

Referring to Fig. 1 of the drawings, there is shown, in a more or lessschematic form, an arrangement of apparatus for carrying out theinvention on a batch basis. The apparatus includes a pressure tank 1, acentrifugal pump 2, a pair of identical reactors 3a and 3b which areadapted for alternate or simultaneous use as hereinafter described, anda cooler or heat exchanger 4.

The pressure tank 1 is adapted to receive oil to be hydrogenated througha pipe 5 that leads upwardly through the bottom of the pressure tank andis provided with three spaced valves 6, 7, and 8. A connecting pipe 9,equipped with a valve for admitting hydrogen gas into the system, joinsthe oil pipe 5 between the first two valves 6 and 7, and anotherconnecting pipe 11 connects the low pressure or inlet side of the pump 2to the pipe 5 between the second and third valves 7 and 3 forwithdrawing a mixture of oil and hydrogen gas from the pressure tank.

The high pressure or outlet side of the pump 2 is connected to a pipe 12for circulating a mixture of oil and hydrogen gas, either directlythrough the heat exchanger 4 and back into the upper part of thepressure tank or also through one or both of the reactors 3a and 3bbetween the pump and the heat exchanger. Oil and gas from the pipe 12may be by-passed through pipe 13a to the reactor 3a and thence throughthe pipe 14a and back into the pipe 12 for return to the upper part ofthe tank 1. Similarly, oil and gas may be by-passed through the pipe13b, reactor 3b, and pipe 14b. A drain pipe 1a with a valve 17 is alsoconnected to the pipe 12 at a low point in the system'for drainagepurposes. A number of additional valves 18a, 18b, 19, 20, 21, 22a, and22b are disposed in the system for controlling the fiow therethrough ashereinafter described. (For convenience later in illustrating how thereactor system of Fig. 2 may be used, an additional branch pipe 23 andvalve 24 have been included in Fig. 1.)

Where the pipe 12 returns to the upper part of the pressure tank 1, itis connected to a spray head 26 inside the tank for breaking up thereturned oil into a fine spray. The atmosphere in the upper part of thetank through which the spray falls is controlled by an exhaust pipe 27,equipped with a valve 28, for exahusting air' and'water vapor therefrom,and by a pipe 29 equipped with a pressure gage 30 and valve 31, forsupplying and maintaining a hydrogen atmosphere in the tank at aselected pressure, as hereinafter described.

The construction of suitable reactors 3a and 3b is shown in detail inFigs. 3 and 4. Each of these illustrative reactors comprises inner andouter, concentric, cylindrical shells 33 and 34 that define an annularreaction chamber therebetween. The shells 33 and 34 may be made: of anysuitable inert material that is a non-conductor of electricity, such asporcelain, ceramic ware, silica glass, quartz, or the like.

The annular reaction chamber is filled with a selfsustaining porous massof a suitable, electrically conductive, catalytic material 36,hereinafter described, and the ends of the chamber are closed by a pairof iden tical heads 37 of a relatively strong, inert, and heat resistantstructural material such as Bakelite, polystyrene, or the like, havinggood dielectric properties. The ends of the cylindrical shells 33 and 34abut against suitable pairs of inert, impervious, and heat resistantgasket rings 38 and 39, respectively, which may be made oftetrafluorethylene (Teflon), a silicone resin, or equivalent ma terial.The gaskets are preferably set into the heads 37 as shown.

The heads 37 are yieldably held against the ends of the cylinders 33 and34, preferably by insulating tie rods 41. These rods may be formed ofany good dielectric material having considerable structural strength,such as Mycalex, Pyrex glass, etc., and having threaded studs 42;secured to their opposite ends. The studs 42 project through aperturesin the heads 37 a sufiicient distance to receive any suitable springwashers 43 and nuts 44 for holding the assembly together with sufficientresilience to accommodate slight, longitudinal, thermal expansion andcontraction of the cylindrical shells 33 and 34. Each of the heads 37 isformed with a hollow, centrally disposed boss 46 forming a conduit thatcommunicates with the reaction chamber through a number of radiallyarranged passages 47. A supply pipe, such as 13a (Fig. l), is connectedto the boss 46 at one end of the reactor, and a discharge pipe, such as14a, is connected to the boss 46 at the other end of the reactor.

An electrical conductor 50, preferably in the form of a copper tube,surrounds the outer cylindrical shell 34 in the form of a coil ofseveral turns that may be substantially coextensive with the reactionchamber in an axial direction. The ends of the conductor are providedwith electrical terminals 51 and 52, to which leads from a suitablesource of high frequency alternating current are connected. Thus,passage of a high frequency current through the conductor 50 creates anelectromagnetic field that induces a current of the same frequency inthe electrically conductive catalytic material 36 in the reactionchamber. A suitable cooling medium may be circulated through the tubularconductor from any convenient source (not shown).

Referring to the modified form of reactor shown in Fig. 5, the capacityof the reactor may be enlarged without substantially altering itsoperation by employing three concentrically arranged cylindrical shells56, 57, and 58, of a suitable insert, dielectric material. The threeshells form two concentric annular chambers that may be filled with anysuitable oil pervious mass of catalyst, such as. the catalytic material36 employed in the reactor shown in Figs. 3 and 4. The ends of theseannular chambers are closed by a pair of identical heads 59 of the samematerial as the heads 37 in Figs. 3 and 4. The ends of the cylindricalshells are abutted against suitable pairs of gasket rings 61, 62, and63, respectively, which are set into the heads of the reactor as shown.The reactor is held together in the same manner as the reactor of Figs.3 and 4 by suitable tie rods 64 yieldably anchored at their oppositeends in the heads 59 of the reactor. Hollow bosses 66 are preferablyformed otf center on the heads 59 in this instance. The hollow bossesare connected to both of the annular reaction chambers by a number ofpassages 67, shown formed in the heads 59, and the bosses arerespectively connected to supply and exhaust pipes, such as 13a and 14a(Fig. l) for conveying hydrogen-laden oil to and from the reactor.

For more efficient induction heating, the single conductor 5-0 employedin the reactor of Figs. 3 and 4 is replaced in this instance by anexternal coil 68 and an internal coil 69 connected in parallel andprovided with terminals 71 and 72 for connection to leads from asuitable source of high frequency alternating current. The external coilsurrounds the reactor in substantially same manner as the conductor 50surrounds the reactor of Figs. 3 and 4. The internal coil 69, however,has its ends extended axially through the heads of the reactor inopposite directions and thence outwardly and into communication with theends of the external coil 68. By employing both internal and externalcoils in this manner a more uniform magnetic field may be inducedthroughout both of the two concentrically arranged reaction chambers. Inother respects the reactor of Fig. 5 is substantially the same inconstruction and mode of operation as the reactor of Figs. 3 and 4.

For the. purpose of the present invention, I prefer to employ analternating current in the range from about 1,000,000 to 2,000,000cycles (1 to 2 megacycles) per second, to obtain the most satisfactoryresults within the efiicient range of presently available power supplyequipment. Lower frequencies down to about 500,000 cycles per second maybe employed with satisfactory results if desired, but the speed of thehydrogenation reaction, or

degree ofhydrog'enation during a given time of contact with thecatalyst, drops off as the frequency drops. Except for the limitsimposed by available power equipment, frequencies greatly in excess of2,000,000 cycles per second: could be employed. Up to as high as 10megacycles the efliciency of the hydrogenation reaction appears-toimprove as the frequency is increased, though the electrical losses alsoincrease. Thus, still higher frequencies may become economicallypractical as improvements are made in power supply equipment, and I donot wish to be limited to any particular maximum frequency.

The mode of operation of the apparatus of Fig. 1 for hydrogenating anyof the unsaturated fatty oils is basically the same. Starting with thesystem empty and all of the valves closed, the operation is preferablyas follows: The valve 28 in the exhaust pipe 27, the valves 19, 20, and21 inthe circulator pipe 12, and the valves 6, 7, and 8 in the oilsupply pipe 5 are all opened so that air in the system may escape and sothat the'pipes 11 and 12, as well as the tank 1, may be filled with oilto the desired level. .Oil .at room temperature is supplied to thesystem through the pipe 5 under the required pressure to fill the tank 1to approximately the level shown in Fig. 1. The valve 6 in the pipe 5is-then closed, vacuum is applied to the exhaust pipe 27, and the pump 2is started for circulating the oil from the bottom of the pressure'tank,through the pipe 11 and pipe 12, and back into the upper part of thetank through the spray head 26, from which the oil is discharged as afine spray. This circulation is continued until the oil has had as muchofits original content of water and dissolved gases removed as possible.

After dehydration and degasification of the oil, as described, theexhaust valve 28 is closed and hydrogen gas under a pressure of about 12to 20 lbs. per sq. in. is introduced into the pressure tank through thepipe 29 while continuing the circulation of oil by means of the pump 2.This condition is maintained until the oil has dissolved as muchhydrogen gas as possible, substantially complete saturation at theprevailing temperature and pressurebeing insured by the constant sprayof oil issuingfrom the spray head 26 into a hydrogenatmosphere and thecontinuous recirculation maintained by the pump 2.

The valves 20 and 21 in the pipe 12 are then closed, and the valves 18aand 22a are simultaneously opened to by-passall of the oil through thereactor 3a. At the same time, the high frequency current is applied tothe terminals of the conductor surrounding the reactor 3a to heat thecatalyst therein by induction. Then the valve 'in the hydrogen supplypipe 9 is cracked partly open while supplying additional hydrogenthrough the pipe 9 at a pressure about 3 to 5 lbs. per sq. in. abovethat prevailing at the gage 39 to insure a constant bleeding of hydrogengas into the pipe 11 and thence through the pump 2 and into the pipe 12.The amount of additional hydrogen, and thus the pressure in the pipe 9,may be varied as desired in accordance with the type of oil beingprocessed, the solubility of hydrogen gas in the oil,.and the number ofdouble bonds to be satisfied during hydrogenation. Thus, a supply ofhydrogen in excess of that which the oil will dissolve at the ambienttemperature is intimately dispersed in the oil by the action of the pump2, and oil that is thus supersaturated with hydrogen gas is passedthrough the reactor 3:: and into intimate contact with the inductivelyheated catalyst therein.

The magnitude of the high frequency current supplied to the reactor isadjusted so that the oil emerging through the pipe 14a reaches aselected maximum temperature. As the heated oil is returned to thepressure tank, it passes through the heat exchanger 4, which may be supplied with a suitable coolant for reducing the temperature ofthe oildown approximately to the starting temperature. ,In this manner, thetemperature of the oil both when entering and leaving the reactor ismaintained 6 substantially uniform for as long as it may be necessary tocontinue the reaction.

The chemical combination of hydrogen and oil in the reactor permits theoil leaving the reactor to dissolve more hydrogen gas. Upon beingreturned to the tank 1, this oil is again sprayed through an atmosphereof hydrogen and is subsequently mixed with additional hydrogen in thepump 2, whereby supersaturation of the oil entering the reactor and anample supply of hydrogen for the hydrogenation reaction taking placetherein are insured.

When substantially complete hydrogenation of the oil has been achieved,there is no longer any absorption of heat by the endothermic reaction,and the heat induced in the catalyst can only be transferred to the oilas sensible heat. Thus, completion of the reaction is evidenced by asudden increase in the temperature of the oil leaving the reactor. Thisis a convenient indication of completion of the reaction, and careshould normally be taken to stop the supply of high frequency current tothe reactor promptly when this point is reached. i

By selecting the proper current intensity, rate of flow of oil, etc.,substantially complete hydrogenation of most oils may be achievedwithout permitting the temperature of the oil leaving the reactor toexceed F.

The effects of changing various conditions of operation may be stated ingeneral terms as a guide in the selection of appropriate conditions ofoperation for a given piece of apparatus. A change in the magnitude ofthe electrical current or in the temperature of the oil entering thereactor produces a corresponding change in the tempera-' ture of the oilleaving the reactor, in the rate of hydro-- genation, and in theprogress of side reactions, though the changes are not necessarilyproportional. A change in the frequency of the electrical current or inthe pressure employed, while maintaining the other operatingconditionsthe same, produces a corresponding change in the rate of hydrogenationwithout substantially affecting the temperature rise of the oil passingthrough 'the reactor or the progress of side reactions. A change in therate of fiow of the oil through the reactor produces an opposite changein the mean temperature rise of .the oil during passage through thereactor and in the degree of hydrogenation resulting from a single passof the oil through the reactor. A change in the degree ofsupersaturation of the oil with hydrogen gas before introducing it intothe reactor produces a corresponding, but less pronounced, change in therate of hydrogenation and 'an opposite change in the life of thecatalyst before regeneration is required. 1

When the reaction has progressed to the desired degree (as determined bythe refractive index of samples taken, for example), the current supplyto the reactor is cut OE and the hydrogen supply valve 10 in the pipe 9is closed. The oil may then be degasified to remove all dissolvedhydrogenand any slight amount of volatile de' composition products thatmay have formed during the hydrogenation reaction, and may then besaturatedwith any suitable inert gas, such as nitrogen. Such a procedureproduces a bland oil by removing volatile decomposition products andrenders the oil less susceptible to subsequent infusion of oxygen fromthe air, thus retarding subsequent natural decomposition during storageor use. This is desirable for many uses to which hydrogenated oils areput. It is generally essential when pro ducing an edible oil,particularly if the oil is to be used as a vehicle for vitamins,hormones, and other food supplements that are highly susceptible tooxidation and 'consequent deterioration.

Such degasification and subsequent saturation with an inert gas mayreadily be accomplished in the apparatus of Fig. 1 by first closing thevalve 31 in'the hydrogen. supply pipe 29, opening the valve 28 in theexhaust line 27, and applying a vacuum to the exhaust line while stillcirculating the oil by means of the pump 2. When degasification iscomplete, the valve 28 is again closed, the valve 31 is, opened, and theinert gas. is supplied under pressure through the pipe 29 to the oil ascirculation there,- of is continued. When saturation with the. inert gashas been accomplished, the supply of nitrogen is continued as. thesystem, is drained through the pipe 16.

Up tothis point, no use for the second reactor 3b has been indicated. Asis obvious from its parallel. relation with the reactor 3a, bothreactors may be used simultaneously to increase the rate ofhydrogenation, and any number of reactors in parallel may be similarlyemployed. Alternatively, and preferably, the reactor 31) is employed asa standby for use when the catalyst. in the reactor 3a requiresreactivation, thus permitting the system to remain in use-while. onereactor is being. serviced, as is re.- quired from time to time.

The. catalyst employed in the reactors may be any electricallyconductive hydrogenation catalyst, though nickel is the best for mostpurposes and is by far the most widely used in commercial processes forhydrogenating fatty oil. I prefer to use what is best described asnickel Wool, the individual fibers being of the general order of two tofive thousandths of an inch in diameter. Thismaterial is economical toproduce by the same methods, used for the production of the ordinarysteel wool of commerce. It is highly pervious. to the fiow of oiltherethrough, drains readily, is easily handled, conforms to thecontours of any shape and size of reaction chamber, and isself-sustaining in the sense that it will not collapse, pack, or becarried away by the oil flowing through the reactor and require removalby filtration. Of equal importance, it has a large surface area for thevolume it occupies, which is essential for obtaining an ample.oilcatalyst contact area.

While nickel Wool is an ideal catalyst for use in the present invention,it is obvious that other hydrogenation catalysts and other forms ofnickel catalyst may be employed. Any finely divided electricallyconductive hydrogenation catalyst, such as platinum, held in the re--actor by' being admixed with a conventional adsorbent support, such asfullers earth, can be employed. Also, coatings of an electricallyconductive hydrogenation catalyst on the, surfaces within anyself-sustaining porous mass, or upon the particles of any granular orfibrous, non-packingcarrier may be employed. Since the chem ical.reaction, the catalytic function, and the many equivalcntz types, of,catalysts for performing that function are well known. in the art, I donot intend the invention to be limitedto the particular type of catalystdisclosed, except as requiredby the appended claims.

When a conductor is disposed in an alternating elec tro-rnagneticfield,a current of the same frequency is induced. in the conductor, and. theflow of current in the conductor necessarily heats the conductor at arate dependent on the magnitude and frequency of the current and. onthe. resistance. of the conductor. With relatively low frequencies, theentire body of the conductor seems to; be heated. The higher thefrequency, the more the heating effect is confined to. the surface ofthe conductor (a phenomenon known as the skin eifect), the depth of theheating being stated to vary inversely with the square of the frequency,and the surface temperature reached being stated to increase with thefrequency and at a rate dependent upon the rateof heat dissipation.

The catalyst 36, being a conductor, and being subjectedto an alternatingelectro-magnetic field of relatively high frequency, is thus directlyheated at its surface- Since the hydrogen-laden oil is in contact withthe heated catalyst surface and the hydrogenation reaction takes placeprincipally, if not entirely, at the oil-catalyst interface, itisapparent that the process of' the invention supp es the heat directly tothe. most critical, reaction zone. Thus, while the temperature at. thatzone maybe. higli only the molecules of oil immediately in that zonereachthe reaction zone temperature. Because the. oil

is relatively high, no part of the oil remains: long at that hightemperature and the mean temperature of the: oil mass in the reactor ata given moment is apparently sub? stantially below the maximum. Forthese reasons, it is believed, an effective hydrogenation temperature(at the oilrcatalyst interfaces) is obtained that is. very consider.-ably higher than the mean temperature of' the oil.

Compared to the prior art processes in which the re-- quiredhydrogenation temperature is achieved by heat-ingthe entire oil mass tothat temperature, two outstanding advantages of the present inventionthus becomeapparent, namely, (a) greatly increased overall thermalefficiency and (b avoidance of the numerous deleterious effects ofholding the oil at. a high temperature for any appreciableperiod oftime.

A further advantage of the process is that the catalyst remains activeover exceedingly long periods of time without regeneration, compared tothe performance of the same. catalytic materials in conventional priorart processes. The inductively heated catalyst'is seemingly far lesssusceptible to catalyst poisons under the conditions of operation. As aresult, the costs of operation are reduced by eliminating much of thecatalyst regeneration time formerly required.

Because it is impossible to measure the temperaturereached by the oil inthe alternating electrical field, due to the effect of the field uponany temperature measuring instrument placed therein, some of theforegoing theory of operation is somewhat conjectural, and I do not wishto be limited by any theory of operation. Moreover, there is evidencethat the full explanation of the operation of my method and apparatusinvolves still more abstruse phenomena than those explained in theforegoing discussion. Based upon the known effects of temperature uponthe rate of the hydrogenation reaction, and estimates of the maximumtemperature obtainable at the oil catalyst interface with a given meantemperature of the oil emerging from the reactor, the rate of hydro--genation far exceeds What could reasonably be expected. I attribute thisto some unknown, or at least unexplained, effect of acceleratedmolecular activity at the oil-catalyst interface due to thehighfrequency current traveling in that reaction zone. It seems probablethat far greater molecular activity is brought about in the reactionzone than could result from heat alone.

The magnitude of the current that should beapplied to the conductor 59,or the strength of the magnetic field that should be created thereby,in'order to achieve a particular result, must be determined empiricallyfor a particular form of reactor and'set of operating conditions, andeven. approximate limits cannot readily be given to define the practicalconditions of operation. The reason for this is that such figures aresubject to wide variation with changes in the many other variables inthe system, such as the physical character of the catalyst, the rate 'ofmovement of the oil over the catalyst surface, the starting temperatureof the oil, the selected maximumtemperature of oil leaving the reactor,the amount of dissolved and dispersed hydrogen in the oil, the type ofoil,

etc., to say nothing of the electrical efiiciency'of the reactor as aninduction heater. Similarly; it isf'irnpossible',

of the character herein described will be useful to illustrate morefully the practice of this invention and for comparison with othermethods and systems.

- The apparatus of Figs. 1, 3, and 4, but with the cooler 4 omitted, wasemployed to hydrogenate certain specific oils selected for illustrative.purposes. The reaction chamber of the reactors 3a and 3b had an innerdiameter of 4 inches and outer diameter of 5 inches, and a length of 18inches. The catalyst employed was nickel wool having fibers ranging from.002 to .004 of an inch in diameter loosely packed to fill the reactionchamber. The input electrical energy was 2,000 watts at 1.5 megacycles.A refined soya beanoil and a refined fish oil were'processedsuccessively in this apparatus and the same soya bean oil was processedin clonventional equipment for comparative purposes.

The conventional hydrogenation process was carried out by suspending afinely divided catalyst in the oil contained in an autoclave,, tl1ecatalyst being nickel deposited on kieselguhr. The autoclavewas providedwith .a steam jacket for heating and with a high speed agitator,

and an atmosphere of hydrogen gas was maintained above the oil. Hydrogengas was continuously bled from the top of the autoclave and reintroducedinto the bottom of the autoclave so as to bubble upwardly through theoil. v t i In the following table the conditions of operation and theresults of the runs on the hydrogenation of the soya bean oil and thefish oil by my high-frequency induction method are given in the firsttwo columns of data, and the conditions of operation and resultsobtained by the conventional hydrogenation process are given in thethird column of data. In each case, initial degassification was carriedout for 20 minutes at 29.95 inches of mercury vacuum.

High Fre- Induction Conventional quency Method Method Type of Oil SoyaBeam. Fish 01L Soya Bean. Starting Temp..- 71 F 68 F 66 F. HydrogenPress" #jsq. in r 10 #/sq. n 100 #/sq. n. 011 Press 10 #/sq. in 10 #/sq.m. 100 #/sq. in. Vol. of charge 5gal. Egal 5gal. 4 Rate of circulation50 gal./hr 50 gal./hr. high speed agitation.

Reaction time.. 29 min Final Temp Final Titre Final free fatty acldsFinal iodine value Final sap. number In the above described experiments,the total amount of heat energy supplied when usingthe high frequencyinduction method was approximately 50% less than that supplied whenusing the conventional process.

Turning now to the apparatus in Fig. 2 of the drawing, there is shown avariation ofthe reactor arrangement for hydrogenating oil on-acontinuous or, semi-continuous basis, rather than on the batch basisdescribed above.

The apparatus of Fig. 1, with the reactors, the pipes for connectingthem to the circulating pipe 12, and the heat exchanger 4 completelyeliminated, maybe used to supersaturate the oil with hydrogen gas, aspreviously described. When saturation of the oil with hydrogen gas iscomplete, the valve 19 in the pipe 12 is closed and the valve 24 in thebranch pipe 23 is opened to discharge the hydrogen-laden oil through thepipe 23 and into the reactor arrangement shown in Fig. 2, from which thefully hydrogenated oil is discharged for such subsequent treatment asmay be desired.

Referring to the details of Fig. 2, there is shown one bank of reactors81a, 82a, and 83a, and a second bank of reactors, 81b, 82b, and 83b, thetwo banks being adapted.

either for alternate use or simultaneous use as desired. Between eachadjacent pair of reactors in a bank, is a cooler or heat exchanger,suchas 84, which may be supplied with any suitable coolant. The twobanks of reactors and coolers are connected in parallel to the pipe 23by means of branch pipes 86a and 86b, respectively, and the reactors andcoolers in each bank are connected in series to form a continuous paththerethrough. The terminal reactors 83a and 83b in the two banks exhaustinto branch pipes 87a and 87b, respectively, and these branch pipes areconnected to a common pipe 88 from which the hydrogenated oil is finallydischarged. Suitable valves are'located in the various pipes asindicated.

It is obvious, of course, that the oil discharged from the pipe 83 mayrequire further cooling, degassification, saturation with an inert gas,etc., according to the use to which it is to be put. Any suitableequipment (not shown) may be connected to the pipe 88 for such purposes.

Each of the reactors 81a, 82w, 83a, 81b, 82b, and 83b may be identicalwith the form of reactor shown in Figs. 3 and 4, or the form of reactorshown in Fig. 5 may be substituted therefor. The coolers betweenadjacent reactors may be of any desired type for using the mostconveniently available cooling medium.

When a given degree of hydrogenation is desired While employing thesystem shown in Fig. l, the reaction time required may be equivalent tocomplete circulation of the oil, for example, twice through a singlereactor. By employing several reactors in series, as in Fig. 2, andcooling the oil leaving one reactor before it enters the next reactor,the same degree of hydrogenation of any given oil may be achieved at thesame maximum mean temperature in the time required to empty the tank 1once at the same pumping rate. It is apparent, therefore, that thereactor arrangement of Fig. 2 may reduce the time required tohydrogenate an oil by as much as or more, depending primarily upon thedegree of hydrogenation desired.

i prefer to have at least three reactors in series to give reasonableflexibility for effecting any desired degree of hydrogenation of anykind of fatty oil which may be processed from time to time. There islittle resistance to the flow of oil through the reactors, and anyexcessive capacity due to the number of reactors in a bank may easily becorrected merely by cutting oil? the electrical current to one or morereactors in the series and cutting off the supply of coolant to anycooler not required, or by reducing the input of electrical energy toone or more of the reactors.

in other respects, the operation of the arrangement of reactors of Fig.2 is essentially the same as the arrangement in Fig. 1. In fact, ifdesired, the reactor arrangement of Fig. 2 may be substituted in thesystem of Fig. 1, thereby reducing the time of circulation of oil duringthe hydrogenation operation without otherwise altering the generalprocedure or arrangement of the apparatus.

From the foregoing, it will be seen that I have provided a method andapparatus having a number of outstanding advantages for hydrogenatingfatty oils. These advantages are manifested in economy of power, greaterspeed and completeness of the reaction, controllability of the reaction,and of side reactions, improved quality of the product, and unusualflexibility to meet all of the requirements for handling diflerent kindsof oils.

In addition, the same apparatus, and particularly the reactorsthemselves, are admirably adapted for carrying out numerous other typesof catalytic reactions in which contact between one or more fluidreactants and a catalyst at an elevated temperature is required. Whilethe specific process disclosed herein is one requiring a carefullimitation of the maximum temperature of the fluid reactants. theapparatus is well suited also for operations requiring much highertemperatures, and higher pressuresas well. Therefore, thougha specificreaction and method have been described in detail and are defined insome of the appended claims, certain aspects of the invention are notlimited to such details except as expressly required by the claims.

Having described my invention, 1 claim:

1. The method of hydrogcnating unsaturated fatty oil, comprising firstsaturating the oil with dissolved hydrogen gas andthereafter passing thehydrogen-laden oil over the surfaces of electrically-conductivehydrogenation catalyst in the form of minute metal fibers, andsimultaneously activating and accelerating movement of electrons at theinterface between the oil and catalyst surfaces by inducing in thesurfaces of the catalyst a high frequency electric alternating currentin the order of one million cycles per second and upward, the magnitudeof induced current being adjusted to produce a mean temperature rise ofthe oil in the range of approximately 20 to 220 degrees F.

2. The method of hydrogenating an unsaturated fatty oil, comprisingfirst saturating the oil with dissolved hydrogen gas and thereafterpassing the hydrogen-laden oil over the surface of an electricallyconductive hydrogenation catalyst while inducing in the catalyst a highfrequency alternative current of at least 1,000,000 cycles per second,the magnitude of the induced current being adjusted to produce a meantemperature rise of the oil of from about 20 to about 220 degrees F, theinitial temperature of the oil being controlled as required as it isrecirculated to limit the mean temperature of oil leaving the catalystto a maximum of about 300 F.

3. The method of claim 2 in which additional hydrogen gas is uniformlydispersed in the hydrogen-laden oil and passed over the catalyst surfacetherewith.

4. T he method of claim 2 in which the magnitude of the induced currentis adjusted to produce a mean temperature rise of the oil during passageover the catalyst surface of from about 20 to about 100 degrees F., theinput temperature of the oil being controlled as required to limit themean temperature of the oil leaving the catalyst to a maximum of about180 F.

5. The method of claim '2 in which the catalyst is a confined mass ofnickel wool, the fibers of the wool having an average diameter in therange of about 2 to 5 thousandths of an inch, and the hydrogen-laden oilis passed through the catalyst mass.

6. The method of hydrogenating an unsaturated fatty oil, comprisingpassing the oil previously saturated with dissolved hydrogen gas andpreviously admixed with uniformly dispersed undissolved hydrogen gasthrough a substantially stationary mass of a metallic hydrogenationcatalyst while inducing in the catalyst a high frequency alternatingcurrent of at least 500,000 cycles per second, the magnitude of theinduced current being adjusted to produce a mean temperature rise of theoil (luring passage through the catalyst mass of from about to about 220degrees F., and the input temperature of the oil being controlled asrequired to limit the temperature of the oil withdrawn from the catalystmass to a maximum of about 300 F.

7. A process for hydrogenating an unsaturated fatty oil, comprisingdegassifying and dehydrating the oil and saturating it with hydrogen gaswhile maintaining it at a temperature not substantially exceeding 100F., then passing a stream of the saturated oil admixed with undissolvedhydrogen gas through a substantially stationary mass of a metallichydrogenation catalyst while inducing in the catalyst a high frequencyalternating. current of at least 500,000 cycles per second, andadjusting the magnitude of the induced current to a value sufficient toeffect l'iydrogenation of the oil without raising the mean temperatureof the oil above 300 F.

8. A process for hydrogenating an unsaturated fatty oil, comprisingdegassifying and dehydrating a body of the oil and then supersaturatingit with. hydrogen gas, passing a continuous stream of the hydrogen-ladenoil through a bed of an electrically conductive hydrogenation catalystand thence back into said body of oil while inducing in the catalyst ahigh frequency alternating current of at least 500,000 cycles persecond, said body of oil being maintained at a temperature notsubstantially exceeding F., and the magnitude of said induced currentbeing adjusted to produce a mean temperature rise of the oil duringpassage through the catalyst bed of from about 20 to about 100 degreesF., and continuing the flow of said stream until the desired degree ofhydrogenation of the oil has been attained.

9. The process of claim 8 in which the flow of said stream is continueduntil a sharp rise in the temperature of the oil passing from thecatalyst bed back to said body of oil indicates that substantiallycomplete hydrogenation of the oil has been achieved.

10. The process of claim 8 in which the hydrogenated oil is againdegassified and then saturated with an inert gas.

11. A process for hydrogenating an unsaturated fatty oil, comprisingdegassifying and dehydrating a body of the oil and saturating it withhydrogen gas at a selected initial temperature, withdrawing from saidbody of oil a continuous stream of hydrogen-laden oil, introducingadditional hydrogen gas into said stream and dispersing it uniformlytherein, passing the stream of hydrogen-laden oil through a stationarybed of an electrically conductive hydrogenation catalyst and thence backinto said body of oil while inducing in the catalyst a high frequencyalternating current of at least 500,000 cycles per second, andmaintaining said body of oil at a temperature not substantiallyexceeding said selected initial temperature, the magnitude of saidinduced current being adjusted to produce a mean temperature rise of theoil during passage through the catalyst bed of from about 20 to about100 degrees F., and continuing the flow of said stream until the desireddegree of hydrogenation of the oil has been attained, as indicated by asharp rise in the temperature of the oil passing from the catalyst bedand which corresponds to substantially complete hydrogenation.

12. The process of claim 11 in which the hydrogenated oil is againdegassified and then saturated with an inert gas.

13. Apparatus for elfecting reaction between a liquid and a gas,comprising means defining an enclosed reservoir, means for charging saidreservoir with a liquid reactant, means for evacuating said reservoir,means for supplying a gas reactant to said reservoir at superatmosphericpressure for solution in said liquid, means for withdrawing said liquidand dissolved gas from said reservoir and circulating it along anenclosed path and back into said reservoir, means defining a reactionchamber interposed in said path so that the liquid flows therethrough, aself-sustaining fluid pervious mass of an electrically conductivecatalyst disposed in said chamber so that the liquid and dissolved gaspass through said mass, and means for inducing a high frequencyalternating current in said catalyst.

14. The apparatus of claim 13 including means for bleeding additionalgas into said enclosed path between the point of withdrawal of liquidand dissolved gas from said reservoir and the entrance to said reactor.

15. The apparatus of claim 13 including means for bleeding additionalgas into said enclosed path between the point of withdrawal of liquidand dissolved gas from said reservoir and the entrance to said reactor,and centrifugal means for forcing liquid along said enclosed path, saidcentrifugal means being interposed in said path between the point atwhich gas is bled into said path and the entrance to said reactor forpromoting uniform dispersion of entrained gas in the liquid.

16. The apparatus of claim 13, including means for removing from theliquid sensible heat supplied thereto in said reactor,

17.. Apparatusfor effecting chemical reactions comprising a pair ofconcentrically disposed cylindrical shells of 1a dielectricmaterial,said shells defining an annular reaction spaced therebetween, a pair ofend closures for said annular reaction space, said end closures beingformed of a dielectric material, means for yieldably holding said endclosures against the opposite ends of said shells to accommodate thermalexpansion and contraction of the shells, a plurality of passagesconnecting said annular reaction space with common fluid passages ateach end thereof, a self-sustaining mass of a liquid perviouselectrically conductive catalyst substantially filling said annularreaction chamber, an electrical conductor encircling the outer one ofsaid shells as a coaxially disposed coil, and means for passing a highfrequency electric current through said conductor.

18. Apparatus'for elfecting chemical reactions comprising a plurality ofreactors arranged in series, each of said reactors comprising walls ofdielectric material defining an annular reaction chamber, aself-sustaining mass of an oil pervious' electrically conductive,hydrogenation catalyst substantially filling said chamber, inletpassages for conducting a fluid into said chamber at a plurality ofcircumferentially spaced points at one end thereof, outlet passages, forconducting fluid out of said chamber from a plurality ofcircumferentially spaced points at the opposite end thereof, anelectrical conductor encircling said reactor as a coaxially disposedcoil, means for passing a high frequency electric current through saidconductor, conduits connecting the outlet of each reactor in the seriesbut the last to the inlet of a succeeding reactor, and means for coolingfluid flow-ing through said conduits between reactors.

References Cited in the file of this patent UNITED STATES PATENTS1,123,962 Walker Jan. 5, 1915 1,124,560 Utescher Jan. 12, 1915 1,181,205Arnold May 2, 1916 1,472,281 Page Oct. 30, 1923 1,621,143 Vogel Mar. 15,1927 2,147,177 Seto et al Feb. 14, 1939 2,257,177 Luster 1 Sept. 30,1941 2,468,799 Ziels May 3, 1949

1. TH METHOD OF HYDROGENATING UNSATURATED FATTY OIL, COMPRISING FIRSTSATURATING THE OIL WITH DISSOLVED HYDROGEN GAS AND THEREAFTER PASSINGTHE HYDROGEN-LADEN OIL OVER THE SURFACES OF ELECTRICALLY-CONDUCTIVEHYDROGENATION CATALYST IN THE FORM OF MINUTE METAL FIBERS, ANDSIMULTANEOUSLY ACTIVATING AND ACCELERATING MOVEMENT OF ELECTRONS AT THEINTERFACE BETWEEN THE OIL AND CATALYST SURFACES BY INDUCING IN THESURFACES OF THE CATALYST A HIGH FREQUENCY ELECTRIC ALTERNATING CURRENTIN THE ORDER OF ONE MILLION CYCLES PER SECOND AND UPWARD, THE MAGNITUDEOF INDUCED CURRENT BEING ADJUSTED TO PRODUCE A MEAN TEMPERATURE RISE OFTHE OIL IN THE RANGE OF APPROXIMATELY 20 TO 220 DEGREES F.
 13. APPARATUSFOR EFFECTING REACTION BETWEEN A LIQUID AND A GAS, COMPRISING MEANSDEFINING AN ENCLOSED RESERVOIR, MEANS FOR CHARGING SAID RESERVOIR WITH ALIQUID REACTANT, MEANS FOR EVACUATING SAID RESERVOIR, MEANS FORSUPPLYING A GAS REACTANT TO SAID RESERVOIR AT SUPERATMOSPHERIC PRESSUREFOR SOLUTION IN SAID LIQUID, MEANS FOR WITHDRAWING SAID LIQUID ANDDISSOLVED GAS FROM SAID RESERVOIR AND CIRCULATING IT ALONG AN ENCLOSEDPATH AND BACK INTO SAID RESERVOIR, MEANS DEFINING A REACTION CHAMBERINTERPOSED IN SAID PATH SO THAT THE LIQUID FLOWS THERETHROUGH, ASELF-SUSTAINING FLUID PERVIOUS MASS OF AN ELECTRICALLY CONDUCTIVECATALYST DISPOSED IN SAID CHAMBER SO THAT THE LIQUID AND DISSOLVED GASPASS THROUGH SAID MASS, AND MEANS FOR INDUCING A HIGH FREQUENCYALTERNATING CURRENT IN SAID CATALYST.